While other political conventions in the post-9/11 era have featured tight security, the volume and repetitiveness of the security at this year’s GOP gathering is noticeable. It reflects the accumulation of knowledge from other similar events.

“Over time, it may not be threat-driven, it just may be security-driven,” Bongino said.

He spoke inside the convention center, where he was making the rounds promoting his campaign with US Senator Ben Cardin, the Democrat he is trying to unseat.

Bongino graduated at the top of the training program to join the elite Presidential Protection Division. He was an agent on the detail protecting President George W. Bush during his final three years on office and then President Obama for the first two years of his term.

He helped coordinate security for one of Obama’s clandestine visits to Afghanistan.

He knows of what he speaks.

“There’s very little discretion in security, especially in an event like this,” said Bongino. “You have to remember, they’re operating - the Secret Service - in a zero-error environment. You can’t afford to miss that one thing. The problem with that sort of zero-error environment you’re working in is 999 of 1,000 (people) who may have no malicious intent whatsoever get caught up in it.”

He said the “age-old” challenge of security is how to provide protection without suffocation.

In the case of Tampa and other potential targets, agents construct boxes within boxes.

That 8-foot fence is part of the outer perimeter. Buildings inside and fencing blocking doors or steering pedestrians toward other entrances help form the middle zone.

The metal detectors and even agents outside the room where presumptive presidential nominee Mitt Romney will be form the inner zone.

“If you don’t have a perimeter, you have open access, you have a free-for-all,” said Bongino.

Nonetheless, he said his former colleagues and all their police brothers are not trying to antagonize convention attendees.

“They’re not here to make your life more miserable. I know it seems that way,” Bongino said. “They really want it to be user-friendly, but security, it’s not always easy to round off the rough edges.”